This invention relates to dielectrics of organic polymers capable of being used in the form of thin layers. The invention also relates to the process for producing the thin layers, to the use of this process for the production of electrical capacitors and to the capacitors having one or more dielectric layers obtained by this process.
It is known that a thin layer of polymer having interesting dielectric properties can be obtained from organic compounds by processes which may be divided into three categories:
First-category processes: a thin layer of polymer can be obtained by immersion of a substrate in a solution of this organic polymer; however, this process is difficult to carry out on an industrial scale for mass production purposes, particularly in the case of capacitors.
Second-category processes: it is known that homogeneous and uniform layers of dielectric can be obtained by the electron bombardment or by the ultraviolet radiation of an organic monomer; however, the rate at which the layer is formed is very low, amounting to around ten Angstroms per minute.
Third-category processes: a layer of polymer growing at a rate of a few hundred to a few thousand Angstroms per minute can be obtained by glow discharge in a gaseous phase of the monomer; however, the dielectric obtained in this way generally does not have all the requisite qualities, namely:
ADEQUATE THERMAL STABILITY, THE DIELECTRIC PROPERTIES DISAPPEARING BEYOND A CERTAIN TEMPERATURE RANGE;
SUFFICIENTLY LOW DIELECTRIC LOSSES, PARTICULARLY AT HIGH FREQUENCIES;
A LOW TEMPERATURE COEFFICIENT, THE CAPACITANCE VARYING TO A GREATER OR LESSER EXTENT AS A FUNCTION OF TEMPERATURE AND FREQUENCY;
A SUFFICIENTLY HIGH ELECTRICAL BREAKDOWN FIELD.
According to the present invention, it is possible by using a process of the third category to obtain a layer of dielectric having a range of properties generally better than that of known polymers at a growth rate which is amongst the quickest.